Invisible scroll bars keep making me miss new messages just because indicators were out of the viewport. Having the browser stall routinely causes full reloads (after a delay, making it more annoying), then the reload is invarialy interrupted by the server due to request overload. Not to mention that the reload is slow already. Long messages show up collapsed, and uncollapsing them often devours whatever text was in the input field, an especially useful feature when trying to write a thoughtful reply cross-referencing multiple posts. Email notifications send out the same message multiple times, and presents author's name the same way as the rest of the text. Constant hitting on the CPU. Confusing notion of threads and forums. I could go on - Zulip is not nice.
